The question itself is a though experiment that brings awareness to questions pertaining to reality and observation. It does not necessarily have a right or wrong answer but was meant to explore the possibility of an unperceived existence. This means that human perception is what defines reality and if it cannot be perceived at a particular moment in time then it is not real, regardless of whether it exists or not. The question was original posed by the philosopher George Berkely, in his work, “A Treatise Concerning the Principles of Human Knowledge”.
To examine this question from an idealist perspective, we will first have to look at the definition of an idealist or idealism. Idealism as a philosophy holds that reality is mental and immaterial, idealist see things as they should be rather than how they actually are. An idealist would answer no to the question because an idealist worldview dictates the superiority of perception. And since no one is there to perceive the event, then it might as well have not occurred.